


Full of Yourself

by dracoqueen22



Series: Crown the Empire [11]
Category: Transformers - All Media Types
Genre: Alt-Mode Sexual Interfacing, Beastmode Sexual Interfacing, Body Modification, Come Inflation, Grimlock Knotting as a TRex, Knotting, M/M, Office Sex, Sticky Sexual Interfacing
Language: English
Status: Completed
Published: 2017-12-27
Updated: 2017-12-29
Packaged: 2019-02-22 19:21:29
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 6,817
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13173537
Author URL: https://archiveofourown.org/users/dracoqueen22/pseuds/dracoqueen22
Summary: Starscream’s been a busy, busy Seeker, and he has a surprise for Grimlock that’s going to make both of them very happy mechs.





	1. Chapter 1

**Author's Note:**

> This is a prompt-fic for JarofDirtyScrews that I let get way out of hand, per the usual. :)

Decepticon Headquarters was a different place late in the evening, when most of the regular staff had returned to their homes, and all that remained was the skeleton crew. Lights were dimmed to conserve energy, or set to motion timers in other places. Corridors found themselves bathed in shadows, and it was so quiet Starscream could hear his wings twitching as they registered air currents.   
  
It was peaceful, like life under Megatron had never been.   
  
But Starscream hadn’t come to headquarters to reminisce. He’d left the comfort and warmth of his private suite to track down his missing leader and mate, who should have been home hours ago, but had probably lost track of time in his office. Paperwork was one of Primus’ cruelest punishments to place on Grimlock’s shoulders.   
  
Starscream would retrieve Grimlock, or distract him. One way or another, Grimlock’s attention would be back where it belonged right now – on Starscream himself. They had a deal. He had a little surprise for his mate, and Starscream was tired of waiting for an opportunity.   
  
The door was locked, but that was no barrier to Starscream. There was no door in the entirety of Iacon that was locked to Starscream, not even anything barred by Grimlock’s code. That had been the agreement.   
  
It beeped satisfaction with his override and granted him entrance. Starscream grinned as he sashayed inside, his mate looking up at him from half-behind a stack of datapads. Surprise echoed in his field. His visor flickered.   
  
“I… didn’t realize it was that late.”   
  
“Of course you didn’t.” Starscream crossed his arms and leaned against the door frame. “You must have gotten that ability to work past several of your alarms from your genitors.” Ratchet and Wheeljack both were notorious for working themselves into exhaustion.   
  
Grimlock snorted and set down his datapad. “That and there is still far too much work to be done, and not enough hands to do it.”   
  
Starscream flicked his fingers. “Cybertron can’t be rebuilt in a day.” He pushed off the frame, letting the door close behind him, as it had been pinging him to do. “Though we nearly managed to destroy it in one.”   
  
Grimlock leaned back, something keen in the angle of his visor. “You didn’t come fetch me just for a rousing debate on who to blame for the war.”   
  
“No, I didn’t.” Starscream smirked and circled around the desk, his fingertips trailing along the scuffed metal, worn with age and salvaged from a bombed out former-university. “I have a surprise for you, and you didn’t even have the decency to come home on time to get it.”   
  
“A surprise?” Grimlock echoed, and his engine rumbled. His visor tracked Starscream’s every movement with something of a hungry gleam. “What for?”   
  
Starscream shrugged. “Because I felt like it.” His lips pulled into a fang-bearing smirk before he took advantage of Grimlock’s pose and slid neatly into his mate’s lap, draping his arms over Grimlock’s shoulders. “Lucky for you, I brought it with me.”   
  
“Is that so?” Grimlock’s hands landed warm on Starscream’s hips, tugging him closer, their pelvic plating coming into delicious contact. “I don’t see it.”   
  
Starscream laughed and slipped his fingers into a seam, plucking at the cables beneath. “That’s part of the surprise.” He leaned in, nipping at the edge of Grimlock’s mouthplate. “We should break in your office properly. Frag me.”   
  
Hands tightened on his hips, thumbs sweeping inward to rub the edges of his interface array. “That’s not a surprise,” Grimlock replied, vocals husky and hungry.   
  
“Isn’t it?” Starscream scraped his denta over Grimlock’s intake, felt the beat of his energon pump against his lips. “I want you to knot me.”   
  
Grimlock shivered, his field pouring over Starscream like liquid fire. “Is that so? Shouldn’t we go back to our quarters for that?”   
  
“What? I’m not good enough for a little illicit office ‘facing?” Starscream leaned back, his elbows against the desk, wing tips fluttering. “Or are you worried you’ll be too distracted in the future, thinking about me overloading on your knot?”   
  
Grimlock’s engine rumbled. “You are dangerous,” he said as he swept his hands up and down Starscream’s sides, thumbs sweeping inward at the lowest point to caress Starscream’s interface array.   
  
“But you’re still going to give me what I want,” Starscream purred.   
  
Grimlock leaned in, the heat of his ex-vents tickling Starscream’s armor. “Always,” he murmured and his thumbs swept tiny circles over Starscream’s array. “Open.”   
  
That was one command Starscream was willing to obey. He licked his lips as he let his panels open, his spike sliding thick and glossy into Grimlock’s fingers as his valve loosed a few drips onto his partner’s groin armor. He’d spent far too long anticipating this little surprise, and his readiness showed.   
  
Not that Grimlock didn’t appreciate it. His engine rumbled again as his fingers found the wetness between Starscream’s thighs, and two curved into him, caressing his inner nodes.   
  
“You’re ready for me,” he observed.   
  
Starscream wrapped his fingers around Grimlock’s wrist and encouraged his mate to deepen the touch. “Well, you’ve been neglecting me.”   
  
Grimlock’s thumb found his anterior node and gave it a firm rub. Starscream groaned and arched his backstrut, heat pooling in his array as his valve rippled.   
  
“Then I owe you more attention.” Grimlock’s other hand curved around Starscream’s waist, fingers dancing along Starscream’s spinal strut.   
  
“Yes, you do.” Starscream poked his lower lip into a pout, one he knew Grimlock couldn’t resist. “And I want more than your fingers.”   
  
A third finger slipped into his valve, teasing every node within reach. “You’ll have to be more specific, love.”   
  
Starscream growled. He reached back, gripping the edge of the desk to brace himself for a nice grind on Grimlock’s fingers. “You already know what I want.”   
  
“Maybe I want to be sure. I want to hear you say it again.” It was Grimlock’s turn to sound smug and self-satisfied as one hand slid up, tweaking Starscream’s wing mounts.   
  
“Rust you,” Starscream hissed and ground his denta.   
  
Heat wafted up against his aft from Grimlock’s array, and Grimlock’s field blazed at his with desire. Sometimes, Starscream forgot how much Grimlock could be a paragon of self-control. And he always did this. He made Starscream repeat himself, and it’d taken months for Starscream to realize it wasn’t because Grimlock was being an aft, it was because he wanted to make sure Starscream actually wanted him.   
  
It warmed him to the core every time.   
  
So Starscream unfurled his field, allowing his affection and his desire to spill into it. He rolled his hips against Grimlock’s fingers. “Spike me,” he demanded, his voice syrupy sweet and hungry. “Knot me. I want every drop of your transfluid.”   
  
There was a moment of silence before he heard and felt the shiver of need run through his mate. Grimlock’s panel kicked open, the hot head of his spike brushing over Starscream’s aft. His hands moved to Starscream’s hips, easing him forward, the tip of his spike painting Starscream’s rim in pre-fluid.   
  
“That, I can do,” Grimlock growled and rolled his hips, grinding his spike-tip against Starscream’s valve, the head teasing him with penetration but only just.   
  
Starscream groaned and grabbed Grimlock’s arms, pulling himself closer to Grimlock’s spike. “Get inside me already,” he moaned, canting his hips to catch the head of Grimlock’s spike with his rim. The glancing touch caressed his anterior node, and he shivered.   
  
Grimlock’s hands cupped his hips, ever so carefully, and with a single rock forward, he breached Starscream’s valve, easing into him. It was a stretch at first, it always was, but Grimlock was so slow, so careful. He let Starscream move at his own pace, unless Starscream demanded more. So he did, moaning out the demand with a roll of his hips as Grimlock sank another few inches into him.   
  
Starscream braced his weight on the edge of the desk and bore down, pushing himself onto Grimlock’s spike, until he was filled completely, the thick head nudging at his ceiling node. He sighed, optics half-shuttering, as pleasure rippled through his array.   
  
Grimlock’s hand slid back down, circling his anterior node with a rub of his thumb. “Good?” he asked.   
  
Starscream licked his lips and clenched his valve, calipers rolling up and down Grimlock’s spike as he let it ground deep. His vents came in sharper bursts, pleasure tightening into a sharp coil inside of him. He lifted and dropped himself, riding Grimlock’s spike, as his mate’s thumb rubbed slippery and warm over his node.   
  
“You’re making me do all the work,” Starscream replied and tipped his head back, baring his intake, knowing that the sight of it revved Grimlock’s engine.   
  
“Only because you put on such a pretty show.” Grimlock rolled Starscream’s nub between two fingers, giving it a pinch that made Starscream’s hips jerk and pleasure spike through his lines. “Will you give me an overload?”   
  
Starscream laughed, deep and raspy. “Oh, that’s inevitable.” He rolled his hips harder, riding the firm length of Grimlock’s spike. His own bobbed at the apex of his thighs, thick and dripping pre-fluid.   
  
Grimlock’s other hand abandoned his hip, instead curling his fingers tight around Starscream’s spike. He started to strong, long, squeezing and perfect, his thumb rubbing over the transfluid slit on every twist.   
  
Starscream groaned. His valve fluttered, charge building to a crescendo in his groin, Grimlock’s spike throbbing and thickening inside of him. His vents quickened as his head tipped back, mouth opened on a pant.   
  
“Let me see it,” Grimlock murmured, both hands working to drive Starscream’s pleasure higher, little zaps of charge zinging through his lines with every twist of Grimlock’s hand and every flicking rub of his fingers. “Overload for me, Star.”   
  
His denta ground together. His hands curled into taloned fists against the desk’s edge. His backstrut curved, driving Grimlock deeper, as he overloaded, charge spilling like blue fire over his armor. His spike spilled into Grimlock’s grip, thin pulses of transfluid, while his valve rippled around Grimlock’s spike. Pleasure beat through his lines in an arrhythmic cadence, until his processor spun, and he sank back into his thrumming frame.   
  
Grimlock remained rigid with him, thick and throbbing, frame trembling with restraint. Such self-control was intoxicating.   
  
Starscream sucked in a careful vent. “You’re going to fry a circuit,” he said, vocals striped with static. He grinned, lazy and satisfied. “Engage your mod, you idiot. Knot me.”  
  
A sound that could only be called a purr rose from Grimlock’s intake. He thrust up into Starscream with little rolls of his hips. “Yes, dear,” he said, cheeky, and his sticky hands moved to Starscream’s hips, moving him with ridiculous ease.   
  
Starscream went languid, giving his frame over to Grimlock’s greater strength, letting himself be lifted and lowered onto the thick spike. The knot was already starting to swell at the base of Grimlock’s spike, the thickness of it rubbing over Starcream’s sensitized nodes and sending zaps of pleasure up his spinal strut.   
  
He hummed, wings twitching, sinking into the sensation.   
  
Pleasure swamped Grimlock’s field, buzzing hot and heavy, surrounding Starscream in a lust-filled haze. He slid his hands back to Grimlock’s arms, fingers teasing into seams to pinch at the cables beneath, and was rewarded with a shudder and another swell of Grimlock’s knot. It was just a shade too big, enough that it caught on his rim with every roll of Grimlock’s hips, catching and tugging at the pliant metal mesh.   
  
Starscream groaned and drew in a sharp vent. He nibbled on his bottom lip, obscene squelching noises echoing in the office, which now smelled of lubricant and overloads.   
And then Grimlock tugged him down again, ground deep, and his knot swelled one more time, far too large to slip back out of Starscream’s valve.   
  
A sigh slipped free of Grimlock’s vents. His spike throbbed as his hands clenched on Starscream’s hips before loosening again, sliding up and down his sides.   
  
“Okay?” he asked, as always, concerned for Starscream’s comfort.   
  
Starscream, however, licked his lips and grinned. “Oh, I’m perfect,” he purred, and rolled his hips, firmly seating Grimlock inside his valve, his rim immediately contracting behind the knot and keeping it trapped within him. His calipers rippled, a rhythmic wave that seemed to massage Grimlock’s spike from knot to head, as if milking him.   
  
Grimlock went still beneath him, his hands cupping Starscream’s chassis, even his vents paused. “Star?”   
  
“I told you I had a surprise.” Starscream dragged a hand down his frame and palmed his own spike, giving it a squeeze. “You’re not the only one who can get a mod.”   
  
Grimlock’s visor flared. His engine rumbled. “That’s why you’ve been disinterested in ‘facing for a week.”   
  
Starscream chuckled. “It can take that long for the adjustments to settle.” He wriggled his hips, activating the rippling sensation again, and catching a strangled noise in his mate’s intake. “Wheeljack tells me you’ve never fully engaged your mod because you’ve never emptied your transfluid tank. That you can’t.”   
  
Embarrassment flickered in Grimlock’s field. “You talked to Wheeljack.”   
  
Heat tinted Starscream’s cheeks. That had been an interesting conversation. “Needs must.” He twitched his hips, clenching around Grimlock’s spike and provoking another shiver from his mate. “He said there’s a safety mechanism built into the mod so that you can’t hurt your partner by releasing too much transfluid.”   
  
“I knew that.” Grimlock’s hands swept up and down Starscream’s sides as if to reassure.  
  
Starscream’s lips pulled into a slow grin. “But what you don’t know is that I came with more than one surprise.” His hand landed on his lower abdomen, giving it a little pat. “I’ve had a small adjustment to make sure that’s no longer a problem. You can overload until you drain your tank. And I can take it.”   
  
Grimlock growled, the sound echoing in his chassis, his grip sliding to Starscream’s hips and tightening. “I love you.”   
  
“I know.” Starscream swallowed down a laugh and slid his hands back around Grimlock’s arms, leaning forward to deepen the press of the spike within him. “Now frag me,” he purred.   
  
The shudder that rippled across Grimlock’s armor, followed by a burst of drizzling heat in his field, was all the confirmation Starscream needed to know his surprise had been very, very welcome.   
  
Hah.   
  
Grimlock would think twice about ignoring him again, now wouldn’t he?   
  


***


	2. Chapter 2

**Notes for the Chapter:**

> This half includes Grimlock fragging Starscream in his T-Rex altmode so if that's not your cuppa, make skip this half. Cheers!

His berth kept twitching and rumbling beneath him, not quite as at rest as it should be, Starscream remarked with poorly concealed amusement. Then again, he was equally to blame, as his wings kept pushing into broad strokes, demanding more and more of the soft, soothing pets. Grimlock’s hands were made of magic sometimes, even if his attention was a little half-sparked at best, most of his processing power consumed by the datapad in his other hand.   
  
Reports, likely. Or maybe he was pretending to catch up on his work and was actually reading one of the adventure datanovels unearthed from the bowels of a collapsed library. The wing-petting was likely automatic then, though it warmed Starscream from the inside out and sent a low buzz to his interface array.   
  
It didn’t help that he was sprawled on top of his much larger mate, the resting rumble of Grimlock’s engine against his cockpit and straight to his spark. Grimlock ran several degrees hotter than Starscream, and that warmth had seeped through his armor to the cables beneath. It would be relaxing, were it not for the sweep, stroke, tweak motion of Grimlock’s hand on his wings.   
  
Starscream wriggled. He started to move into the pets, backstrut arching, legs shifting restlessly, turbines spinning with a quiet click, click, click. His own datapad fell from slack fingers, interest in the scientific text forgotten. A purr rose in his intake as he squirmed on top of Grimlock, their armor sliding together in a chirr of metal on metal.   
  
He felt the heat of Grimlock’s gaze shift to him, interest in his datapad melting away. Starscream smirked to himself and stirred a bit more, wing pushing up into Grimlock’s hand, his aft wiggling, one leg sliding over Grimlock’s thigh.   
  
“You know,” Starscream purred as he lounged and squirmed just enough to straddle Grimlock’s belly, the heat of his array pressed over his mate’s abdominal vents. “Thundercracker is on shift now, and Cyclonus takes over after that. I believe that means we have what could be considered free time.” He curled his fingers into armor seams, the tips of his talons caressing the cables beneath.  
  
Amusement rumbled in Grimlock’s chassis, vibrating against Starscream’s fingers. “Is that so?” His visor lit with interest, datapad falling by the wayside. “You look like you have something in mind.”   
  
Starscream rolled his hips, grinding down against Grimlock’s belly, heat in his array building to a hungry want. It was rare they shared two off-shifts back to back, rare he could indulge. He knew what he wanted. He knew he wouldn’t even have to beg for it. All he had to do was ask.   
  
He leaned forward, knees pressing in against Grimlock’s sides, wings pushing into the caress of Grimlock’s hand. “Knot me,” he murmured and swept his glossa over his lips, biting back a smirk as Grimlock’s visor tracked the motion of it.   
  
He wasn’t entirely sure that counted as a request. Not when it emerged more as a demand, and a desperate one at that.   
  
But Grimlock’s field surged, hot and hungry. One hand slid from Starscream’s wing to his aft, fingers stroking the curve of it. “You sure?”   
  
Starscream’s spark fluttered. There was something about the single question, the constant need for permission and reassurance, that made his arousal blaze and the affection he felt for his mate deepen and settle in every inch of his frame.   
  
He leaned forward, draped himself over Grimlock’s chest, finding the edge of Grimlock’s mouthplate with his denta. “Someday, you’ll realize I mean what I say and stop asking me that,” he murmured.   
  
Grimlock’s hand curved around his aft and further down, fingers slipping between his thighs to rub over Starscream’s valve panel. He graciously allowed it to spiral open, letting Grimlock slip a finger into him, the thick digit stirring through lubricant to tease the sensory nodes decorating the metal mesh. Starscream moaned and kneaded at his chest, hips sinking down onto the single finger, his valve cycling tight and milking it for more.   
  
“Never.” Grimlock slipped in a second finger, lubricant rolling thick and slick over the digits, making wet noises.   
  
Starscream sucked in a sharp ventilation, heat winding a thready path through his lines. He ground against Grimlock’s chassis, spike throbbing in its sheath, valve hungry and willing, clenching around Grimlock’s fingers. Their fields intertwined, hot and heavy, pulsing to the same needy beat. A moan caught in Starscream’s intake, threatening to spill out.   
  
Grimlock tweaked an aileron, making Starscream shiver. “Want to stay on top or…?” He trailed off, leaving all of the choices to Starscream, as he so often did.   
  
“Mmm, no.” Starscream draped himself over Grimlock’s chassis, languid and aroused, lips curving into a pleased smirk. Want yawed inside of him, processor supplying naughty images that made his energon boil. “I want you to transform for me.”   
  
Grimlock’s engine roared, as Starscream knew it would. His hand tightened on the edge of Starscream’s wing. His fingers pushed deep into Starscream, knuckles grinding on his valve rim, and heat rose up from his groin like a needy inferno.   
  
Starscream hummed a laugh. “I thought you might like that.” He knew how much his trust meant to Grimlock, because Grimlock knew how hard it was for Starscream to give it. Trusting Grimlock in his alt-mode, so much larger, primal, terrifying, was worth thrice as much.   
  
Starscream’s glossa swept over his lips. He pushed himself upright and leaned back into the cradle of Grimlock’s hand, trailing fingers down the front of his chassis to plunge them between his thighs. He toyed with his anterior node, fingers slippery with lubricant and sending pleasure radiating through his array.   
  
“Knot me, my lord,” Starscream purred, fixing Grimlock with a heated look, slipping another finger into his valve, beside the two Grimlock had offered. “Until you’ve given me every drop.”   
  
Grimlock’s visor flashed, and he growled. He surged upward, strong hands gripping Starscream and turning him onto his front on the berth, sliding three fingers into Starscream all at once, pushing deep to stroke his throbbing ceiling node. Starscream moaned and bucked onto the fingers, knees digging into the berth, fingers tangling in the covers.   
  
The heavy mass of his mate settled over him, the front of Grimlock’s thighs rubbing against the back of Starscream’s, Grimlock’s engine revving a heavy vibration against Starscream’s wings. His mate’s hot vents blasted down through his seams, and Grimlock’s fingers rubbed and curled against sparking nodes.   
  
“I thought you might enjoy that,” Starscream gasped as Grimlock’s palm ground against his rim, a heavy pressure on both his upper and lower external nodes. The tiny nubs throbbed with need, swollen and hungry. Lubricant slopped out of his valve, sticky on Grimlock’s fingers, painting the back of his thighs.   
  
“You are a menace,” Grimlock growled, the hunger in his vocals as evident as the need buzzing through his field, and the way he carefully added a fourth massive finger, stretching the limits of Starscream’s valve.   
  
“I thought that was what you liked about me.” Starscream gasped a laugh and kneaded the berth, knees rocking against it to push harder onto those fingers. It was not quite enough anymore, not now that he’d felt the swell of Grimlock’s spike, and more than that, the stretch of his knot.   
  
Starscream hummed deep in his intake. “Transform, my lord,” he said, knowing how much it revved Grimlock to hear the title. “My valve could use some oral attention first.” He spread his knees further, completely baring himself, wisps of air caressing his valve where Grimlock’s fingers left him.   
  
“Your wish is my command.” Grimlock pressed his head to the side of Starscream’s, his hands a caress against Starscream’s sides before he pulled back, sliding off the berth.   
  
His hands tracked down to Starscream’s hips, pulling him nearer to the edge of the berth, all the better to give him easy access. He palmed Starscream’s aft, thumbs sliding down to bracket Starscream’s valve, giving it a brush. Grimlock rumbled again, and Starscream smirked over his shoulder, watching lust darken Grimlock’s visor, and a spill of charge dance bright-blue over his armor.   
  
Grimlock stepped back from the berth, and his field rippled with hunger seconds before he transformed, his alt-mode towering over the berth and Starscream. Anticipation sent shivers through Starscream’s plating even as he pressed his forehead to the berth and pushed his aft up.   
  
Then there was a snout between his legs, nosing between his thighs, the glossa following, big and thick and wet. It lapped at his valve, caressed his nodes, and more pleasure radiated outward, turning Starscream’s cables to liquid. He buried his face in the berth cover, knees wriggling as wide as he could manage, hips rocking back toward Grimlock’s eager licks.   
  
Front nub to valve fold to lower nub and back again, lubricants mingling and turning him into a dripping mess. Starscream quivered, his valve swelling and hot, pleasure building to a fine throb in his array. He writhed, berth covers ripping beneath his talons, balancing on the precipice of overload. He pushed back against Grimlock, into the plunge of a thick glossa over his valve and the delicate scrape of massive denta.   
  
“That’s-- that’s good,’ Starscream gasped out as his aft rocked and his entire frame trembled. “You can… frag me now.”   
  
A growl rumbled in the back of Grimlock’s intake, sounding both smug and hungry. The flat of his glossa laved Starscream’s valve again before he drew back, glossa sweeping over the lubricants painting his snout. His forearms, stunted though they were, patted Starscream’s aft and a following click was barely audible over the combined roar of their cooling fans.   
  
Starscream moaned as he felt the heavy, blunt weight of Grimlock’s spike nudge his aft and the back of his thighs. The dripping tip left streaks of pre-fluid over his armor, painting it in lurid streaks. Grimlock rolled his hips, but in alt-mode, the angle was too awkward for a proper thrust.   
  
He would need help.   
  
Starscream dropped his weight onto his cockpit and reached down, back between his thighs, fingers curling around the bulbous tip of Grimlock’s spike. His mate shivered, releasing a low growl, especially as Starscream guided the dinobot’s spike to his valve, the thick head of it grinding against his rim. As thick as three fingers and ringed with tiny sensor nodes, Grimlock’s spike was a marvel.   
  
Starscream shuddered as he imagined how it felt to pierce him. His lubricant painted the tip, already dribbling with pre-fluid. Grimlock thrust into his grip, grinding against Starscream’s rim and exciting the ring of tiny nodes.   
  
Awkward though the angle might be, Starscream flirted his fingers up and down the length of Grimlock’s spike, ignoring the ridges and bumps, teasing his mate. Grimlock rumbled, venting hot puffs down over Starscream’s frame, his field pushing at Starscream in silent demand to move faster.   
  
Starscream gnawed on his bottom lip. “Now who’s the impatient one?” he asked as Grimlock thrust into his hand again, grinding on the rim of Starscream’s valve.   
  
“You’re being a tease,” Grimlock rumbled.   
  
Starscream barked a laugh and braced his weight on one arm. He guided the tip of Grimlock’s spike to his valve and rocked backward, the head of it parting the pleats of his rim and sinking into his valve. Starscream moaned as pleasure radiated outward, his fingers abandoning Grimlock’s spike to brace himself with both hands now. His knees went weak, wings sinking against his back, as his valve rippled, dangerously close to overload once more.   
  
Grimlock’s engine sent a heavy growl that vibrated them both. His feet braced on the floor before he rolled his hips forward, thrusting deeper into Starscream, half of his spike filling Starscream by the second thrust. Starscream growled and pawed at the berth, blindly shoving back with his knees as Grimlock rocked forward and bottomed out on another thrust, the head of his spike grinding over Starscream’s ceiling node.   
  
Overload shattered through his system. His valve rippled and clenched around Grimlock’s spike, spilling charge into the receptor nodes as it crawled over his armor. Starscream moaned, the berth covers torn by his talons, pleasure spiking through his lines in wave after wave of ecstasy.   
  
Grimlock waited, lingering in Starscream’s valve, frame trembling from the effort of holding himself back, ex-vents scorching where they buffeted Starscream’s frame.   
  
“Good?” he rumbled, vocals rough and tantalizing in Starscream’s audials, making him shiver all over again.   
  
“Always.” Starscream panted, his valve twitching as it fed off the charge in Grimlock’s spike. “Keep going.”   
  
“You’re sure?” Grimlock asked, though his hips moved in a single thrust, rocking Starscream on the berth, stimulating his internal nodes through the thickness of his spike alone.   
  
Starscream moaned. It was all the answer he could manage, through the pleasure sparking in his lines and throbbing in his spark.   
  
Grimlock rumbled at him, field a hot and heavy stroke down the length of Starscream’s. And then he thrust, hard enough to push Starscream a bit further up the berth, his knees tangling in the covers. Starscream moaned again and shoved back, rocking the heavy length inside of him, his aft meeting the armoring of Grimlock’s abdomen. Rhythm soon followed, Grimlock making aborted little thrusts, dragging the nodes of his spike against the crackle-snap of Starscream’s valve.   
  
“F-fill me,” Starscream stuttered, his vocals caught with static, his oral vents coming in sharp pants as his cooling fans roared. He was lost to the rhythm, the press of Grimlock’s spike, the way it ground deep inside of him, building his arousal to new heights.   
  
Grimlock growled, a primal sound, and thrust into him again, shoving Starscream further up the berth. The first hot flush of transfluid spurted into Starscream’s valve, and he felt the swelling at his rim, minute at first, as it always was. Grimlock’s rhythm stuttered, less cadenced and more like desperate humping, the smack of his frame against Starscream’s aft, and the spurt of his spike, hot transfluid washing over Starsream’s nodes.   
  
The knot swelled more with every thrust, filling and filling despite every spurt of searing transfluid, making Starscream twitch and writhe. His awareness narrowed down to a pinpoint, to the ecstasy building in his valve, making him tremble. Grimlock’s spike rasped in and out of his valve, raking over his sensor nodes, until at least, the knot was too large to be removed, and it passed by Starscream’s rim and was trapped within.   
  
Starscream’s mod, only once tested before, contracted immediately. It tightened behind the knot, keeping it within his valve, the bulbous mass of it grinding against the ring of nodes behind Starscream’s rim. He moaned, going limp, as the knot swelled and transfluid filled his valve, stretching the lining, his calipers, straining the limits.   
  
Grimlock sank against him, hips still working in tiny jerks, transfluid filling Starscream’s valve in steady spurts. The pressure built inside of him, the flood of transfluid rushing over Starscream’s nodes, and the tiny opening at the back of his valve, the one that led to his modded overflow tank. It bowed inward at the pressure, until it hit critical and the safety mechanism kicked in, the opening cycling open.   
  
Transfluid rushed into it, sliding over previously untouched sensors along the way. Starscream writhed on Grimlock’s spike, panting as Grimlock spurted more and faster, filling his tank as fast as Starscream’s valve emptied into it.   
  
Grimlock leaned harder against him, mass pinning Starscream’s frame down, his field winding around Starscream and stroking him with intangible fingers. “I love this mod,” he growled.   
  
Starscream couldn’t hide the waves of self-satisfaction in his field. “I seem to remember saying the same thing about yours,” he gasped out as he went completely limp, his frame at Grimlock’s mercy and wracked with pleasure.   
  
Heat crackled through his sensory lines, and his spark whirled and flared with oncoming overload. He was pinned and impaled, helpless almost, and if it weren’t for the trust flooding his spark, he’d have been afraid. But all he felt was arousal.   
  
He deliberately clenched his valve, sending a ripple through the fluids filling him. His calipers strained and fluttered, the shift of pressure like a stroke to his charged internal nodes. More charge crackled between Grimlock’s spike and Starscream’s valve, nodes exchanging energy at a rapid pace.   
  
“I don’t mod myself for just anyone, you know,” Starscream added as the overflow tank started a register its fullness, nearing maximum capacity, the heaviness of it pushing at Starscream’s internals, causing the gaps in his abdominal plating to widen and bulge.   
  
Grimlock rumbled a laugh at him, his tone heavy with arousal. He rocked against Starscream, making his entire frame sway on the berth, the knot so firmly trapped within him that it ground against the interior of Starscream’s rim. It swelled and swelled with every pulse of transfluid, until Starscream’s overlow tank and valve both strained and could hold no more. Not even the rocking of their frames allowed the fluid to budge and Starscream trembled at the sensation.   
  
He pressed his forehead to the berth and panted, claws curled into the cover, rending tears that would have to be mended again. The pressure was intense, delicious, like a constant press on internal nodes no finger could reach, and a spike only rarely.   
  
Grimlock’s engine rumbled. One foot pawed the ground; Starscream could hear the talon scraping the polished metal. Grimlock leaned forward, over Starscream, the weight of him hot and present and arousing. The shift made for the slightest change in angle, nearly minute, except that the head of his spike now ground against a different node.   
  
Pleasure sparked sharp and vivid through Starscream’s array, so startling that it sent him sailing into overload, a low wail escaping his intake. He squirmed, the tightening rim of his modification massaging Grimlock’s knot and milking it. Starscream sagged, panting, a twitch in his lower half.   
  
A glossa swept over the back of his wings, hot and wet. Denta scraped delicately in its wake, and Starscream shivered again. Grimlock growled, the vibrations carrying against Starscream’s wings, as his mate’s spike pulsed in his valve, the knot throbbing to the same rhythm. Grimlock didn’t thrust so much as he lingered, savoring the press and clench of Starscream’s valve around his spike.   
  
Starscream hummed and slipped a hand beneath himself, fingers gathering up lubricant and sliding over his own anterior node. It was plump and throbbing to the touch, eager for stimulation. Starscream gritted his denta, pinching and rolling the tiny tub, little zaps of charge dancing through his valve. Grimlock rocked hard against him, grinding on the outside of his rim, a press of plating on his lower node, and Starscream shuddered.   
  
Overload pulsed through his system all over again, a long, slow wave of bliss that stole his vents. Starscream whimpered with delight as his valve rippled, sending charge racing through the fluid filling him, licking at Grimlock’s spike. His mate growled, low and deep and guttural, and a thick, hot jet of transfluid erupted from his spike, the last of it.   
  
Starscream sighed a moan and slumped into the berth. His valve continued to twitch around Grimlock’s spike, milking the knot to encourage it to shrink. He cupped his abdomen, feeling the bulge of the overflow tank pushing at his plating. It bowed visibly outward, and while that should make him feel ashamed, or ridiculous, it didn’t. Instead it was deliciously erotic, and Primus if he knew why. He supposed it didn’t matter.   
  
He should feel helpless. Trapped. Afraid. But he wasn’t. If anything, he felt erotic, loved, cared for. Grimlock’s field wrapped around him like a loving embrace. A promise.   
  
“It still surprises me you want this,” Grimlock murmured, his vocals rougher in his alt-mode, rasping as they did through sharpened denta.   
  
Starscream folded his arms under his head and manually rippled his valve, making it clench around Grimlock’s spike. He didn’t need to ask why his trust was still a surprise. He could only imagine the ugly things Grimlock had heard over the years, even from his own so-called allies.   
  
“Some probably say it’s a surprise that you want me,” Starscream replied, and was glad Grimlock couldn’t see his face, though his mate could probably read the emotion in his field.   
  
Grimlock growled, bestial and possessive. “Frag them.”   
  
Starscream chuckled. “I’d prefer it if you fragged me.”   
  
His rim mod rippled, massaging the knot at the base of Grimlock’s spike. He supposed this would be odd to the outside viewer, Grimlock in alt-mode, his spike locked in Starscream’s valve, the two of them chatting as they waited for the knot mod to complete its cycle. It still surprised Starscream that it had never once felt weird, only oddly comfortable.   
  
“Isn’t that what I’m doing?”   
  
“And oh so well at that,” Starscream purred. He arched his back, causing the tiniest of shifts to the spike within him, sending out another wave of liquid pleasure.   
  
Grimlock chuckled, and Starscream could hear his tail swishing lazily across the floor. He licked the back of Starscream’s neck again, his frame practically humming with the low-grade pleasure constantly running through him.   
  
He’d described the knotting protocols to Starscream before, how once the knot was fully engaged, his entire array set off wave after wave of tiny overloads that left him floating in a cloud of ecstasy. Focus was hard to come by, and Grimlock managed it only by reaching outside of himself, making sure Starscream was comfortable and pleased.   
  
The knot shrank much slower than it swelled, in incremental shifts. For those who thought Grimlock had no patience, clearly they’d never shared a berth with him. Here they were, tied together for a certain length of time, and Grimlock never tried to jerk away, to urge the process along. If anything, he seemed to relish the time they spent tied.   
  
It wasn’t a strain for Starscream either. The berth supported his weight, and all he had to do was rock a little to stir the spike in his valve, the pressure dancing along his sensory nodes and giving him little bursts of pleasure. It was like a long, slow extended overload for him as well, and he knew when they’d both soaked into it, because conversation vanished. Their fields intertwined, pulsing together, and Starscream hummed as his valve rippled with wave after wave of genuine bliss.  
  
It didn’t end until Grimlock softened enough to slip out of him, the bulge of his knot caressing Starscream’s rim as it eased free, giving him one last strut-shivering overload. Starscream moaned and sank like liquid onto the berth as Grimlock’s heat abandoned his frame.   
  
He heard his mate transform, and the creak of cables being stretched before the berth dipped. Starscream moved to stretch, but was first picked up and deposited in Grimlock’s lap, optics twirling as he was faced with the ceiling and Grimlock leaning over him, worry dimming his visor.   
  
“You didn’t extend your spike?” Grimlock sounded surprised as he traced his finger over Starscream’s spike panel. His other hand palmed Starscream’s belly, curving across the rounded fullness of Starscreamm’s abdomen.   
  
He enjoyed doing that, Starscream noticed. His fingers stroking and measuring the bulge, as if awed and possessive all at once. Starscream thought it was the Earth coming out in him, how he’d been raised on it and all too used on the organic method of reproduction. Something primal, Starscream supposed, about implanting seed into a mate and watching it grow into a new being. Given the organic nature of Grimlock’s alt-mode and his odd field and coding, it only made sense.   
  
“Mmm. Not this time.” Starscream stretched his arm above his head and wriggled until he could turn on his belly, all the better to be draped in his mate’s lap. “Pet me.”   
  
“As if I could do anything less.”   
  
One hand obeyed, stroking Starscream’s back and wings and aft, the steady rhythm a soothing caress that almost lulled Starscream into recharge. Occasionally, it would dip between Starscream’s thighs, stroking the swollen pleats of his valve and dragging through the tiny trickles of dribbling fluid.   
  
Before, playing with Grimlock’s knot had produced a torrent of mess afterward. Since Starscream had gotten the rim mod and Grimlock could fully empty his transfluid tank, however, mess was a thing of the past. A fully-engaged knot contained a compound, in the final spurt, that created a plug of some sort. One which could be dissolved by array-safe solvent at their convenience.   
  
Until then, Starscream would be stuffed with Grimlock’s transfluid, his abdomen rounded, his overflow tank straining, and his valve calipers struggling to grasp the fluid sloshing about. It was maddening and arousing both, but knowing that Starscream was filled with his spill made Grimlock revved beyond belief.   
  
“You’re messy,” Grimlock observed as his finger traced Starscream’s rim, playing in the trickle of fluids gathered there. His tone was less chastisement however, and more possessive, more pride and full of lust.   
  
Starscream smirked. “I guess you’ll just have to clean me up then. It is, after all, your mess.” He arched his aft into Grimlock’s hand pointedly, a lazy curl of heat in his groin from the gentle, exploratory touches.   
  
Grimlock rumbled at him. “Should I take you into the washrack then?” he asked, his voice growing darker, hungrier. “Or would you prefer my glossa?”   
  
Mmm. Decisions, decisions. One was more erotic than the other, but it also would only make Starscream stickier. He was going to have a hard time getting clean in the future as it was. Lubricant was ever so difficult to get out of his joints.   
  
He squirmed onto his back as Grimlock’s hand slid from his aft to resting over his pelvic array. But then, it almost immediately slid up, dragging lubricant with it, to cup Starscream’s lightly rounded belly again. His palm formed a curve over it, thumb stroking strained armor panels.   
  
“Washrack first,” Starscream said and slid his hand up Grimlock’s chassis, one talon tracing the Decepticon badge so prominent there. “After that, we’ll see. We have two whole shifts to ourselves after all.” Barring any emergencies that is.   
  
“Then I plan to enjoy every moment of it,” Grimlock purred and swept Starscream up into his arms, head tilted in for a nuzzle as he slid off the berth heading on a direct route for their private washrack.   
  
Those reports weren’t going to get done in a timely manner, Starscream mused.   
  
Oh, the frag well.   
  


****


End file.
